BMJ  2004;329 (2 October), doi:10.1136/bmj.329.7469.0-f

Filler

POEM^*

Soy protein isoflavones do not reduce postmenopausal complications

Question Do isoflavones improve cognitive function, bone mineral density, and plasma lipids in postmenopausal women?

Synopsis Recent trials have not shown a benefit of postmenopausal oestrogen in improving cognitive function, reducing cardiovascular complications, or maintaining long term protection against fractures. These authors evaluated whether naturally occurring plant isoflavones (phytoestrogens) can be used as an effective alternative for traditional oestrogen therapy. They assigned 202 healthy postmenopausal women aged 60 to 75 years in a double blind fashion (uncertain allocation concealment) to receive 25.6 g of soy protein containing 99 mg of isoflavones (52 mg genistein, 41 mg daidzein, and 6 mg glycetein) or matching placebo on a daily basis for 12 months. Although not specifically stated in the manuscript, contact with the authors clarified that outcomes were assessed by individuals blinded to treatment group assignment. Follow up was complete for 86% of the original participants. On intention to treat analysis, cognitive function, bone mineral density, and plasma lipids did not differ significantly between the two groups. The study had an 80% power to detect a 13% improvement difference between the two groups on the cognitive function test.

Bottom line Postmenopausal supplementation with soy protein containing isoflavones does not improve cognitive function or affect bone mineral density or plasma lipids. Previous studies evaluating an effect of isoflavones on postmenopausal hot flushes have also found minimal benefit.

Level of evidence 1b (see www.infopoems.com/levels/html). Individualised randomised controlled trials (with a wide confidence interval).

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Kreijkamp-Kaspers S, Kok L, Grobbee DE, et al. Effect of soy protein containing isoflavones on cognitive function, bone mineral density, and plasma lipids in postmenopausal women: a randomized controlled trial. JAMA 2004;292: 65-74[Abstract/Free Full Text].

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^* Patient-Oriented Evidence that Matters. See editorial ( BMJ 2002;325: 983[Free Full Text])

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